| Message ID | 20230217191515.166819-3-tirthendu.sarkar@intel.com (mailing list archive) |
|---|---|
| State | Awaiting Upstream |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | i40e: support XDP multi-buffer | expand |
>-----Original Message----- >From: Intel-wired-lan <intel-wired-lan-bounces@osuosl.org> On Behalf Of >Sarkar, Tirthendu >Sent: 18 February 2023 00:45 >To: intel-wired-lan@lists.osuosl.org >Cc: Sarkar, Tirthendu <tirthendu.sarkar@intel.com>; netdev@vger.kernel.org; >Brandeburg, Jesse <jesse.brandeburg@intel.com>; Nguyen, Anthony L ><anthony.l.nguyen@intel.com>; bpf@vger.kernel.org; Karlsson, Magnus ><magnus.karlsson@intel.com> >Subject: [Intel-wired-lan] [PATCH intel-next v6 2/8] i40e: change Rx buffer size >for legacy-rx to support XDP multi-buffer > >Adding support for XDP multi-buffer entails adding information of all the >fragments of the packet in the xdp_buff. This approach implies that >underlying buffer has to provide tailroom for skb_shared_info. > >In the legacy-rx mode, driver can only configure upto 2k sized Rx buffers and >with the current configuration of 2k sized Rx buffers there is no way to do >tailroom reservation for skb_shared_info. Hence size of Rx buffers is now >lowered to 1664 (2k - sizeof(skb_shared_info)). Also, driver can only chain >upto 5 Rx buffers and this means max MTU supported for legacy-rx is now >8320. > >Signed-off-by: Tirthendu Sarkar <tirthendu.sarkar@intel.com> >--- > drivers/net/ethernet/intel/i40e/i40e_main.c | 2 +- >drivers/net/ethernet/intel/i40e/i40e_txrx.h | 1 + > 2 files changed, 2 insertions(+), 1 deletion(-) > Tested-by: Chandan Kumar Rout <chandanx.rout@intel.com> (A Contingent Worker at Intel)
diff --git a/drivers/net/ethernet/intel/i40e/i40e_main.c b/drivers/net/ethernet/intel/i40e/i40e_main.c index d375d7940308..49e6cd1ef6cd 100644 --- a/drivers/net/ethernet/intel/i40e/i40e_main.c +++ b/drivers/net/ethernet/intel/i40e/i40e_main.c @@ -2903,7 +2903,7 @@ static void i40e_sync_filters_subtask(struct i40e_pf *pf) static u16 i40e_calculate_vsi_rx_buf_len(struct i40e_vsi *vsi) { if (!vsi->netdev || (vsi->back->flags & I40E_FLAG_LEGACY_RX)) - return I40E_RXBUFFER_2048; + return I40E_RXBUFFER_1664; return PAGE_SIZE < 8192 ? I40E_RXBUFFER_3072 : I40E_RXBUFFER_2048; } diff --git a/drivers/net/ethernet/intel/i40e/i40e_txrx.h b/drivers/net/ethernet/intel/i40e/i40e_txrx.h index 768290dc6f48..1382efb43ffd 100644 --- a/drivers/net/ethernet/intel/i40e/i40e_txrx.h +++ b/drivers/net/ethernet/intel/i40e/i40e_txrx.h @@ -97,6 +97,7 @@ enum i40e_dyn_idx_t { /* Supported Rx Buffer Sizes (a multiple of 128) */ #define I40E_RXBUFFER_256 256 #define I40E_RXBUFFER_1536 1536 /* 128B aligned standard Ethernet frame */ +#define I40E_RXBUFFER_1664 1664 /* For legacy Rx with tailroom for frags */ #define I40E_RXBUFFER_2048 2048 #define I40E_RXBUFFER_3072 3072 /* Used for large frames w/ padding */ #define I40E_MAX_RXBUFFER 9728 /* largest size for single descriptor */
Adding support for XDP multi-buffer entails adding information of all the fragments of the packet in the xdp_buff. This approach implies that underlying buffer has to provide tailroom for skb_shared_info. In the legacy-rx mode, driver can only configure upto 2k sized Rx buffers and with the current configuration of 2k sized Rx buffers there is no way to do tailroom reservation for skb_shared_info. Hence size of Rx buffers is now lowered to 1664 (2k - sizeof(skb_shared_info)). Also, driver can only chain upto 5 Rx buffers and this means max MTU supported for legacy-rx is now 8320. Signed-off-by: Tirthendu Sarkar <tirthendu.sarkar@intel.com> --- drivers/net/ethernet/intel/i40e/i40e_main.c | 2 +- drivers/net/ethernet/intel/i40e/i40e_txrx.h | 1 + 2 files changed, 2 insertions(+), 1 deletion(-)